The present invention generally relates to materials suitable for use in heating, ventilating, and air-conditioning (HVAC) ducts. More particularly, the invention relates to an insulation material that can be used as an external duct wrap or an internal duct liner, and is capable of providing noise suppression, thermal protection and, if used as an internal duct liner, does not expose the airstream within the duct to harmful fibers.
With the advance in HVAC duct design, much larger ducts are required to move air from both hot and cold air sources. The movement of air through a large duct system can generate a significant level of noise, as well as a need for more effective thermal protection as compared to smaller ducts. For this reason, external duct wraps that surround the duct exterior and internal duct liners that line the interior surfaces of the duct have been proposed. Flexible wraps and liners containing fibrous insulation materials (e.g., fiberglass) have typically been the material of choice for meeting these challenges, though if used as a duct liner there can be a concern for harmful fibers becoming entrained in the airstream, especially in hospitals, nursing homes, and schools. Another approach that has been proposed is to use rigid or semirigid insulation board materials. While generally avoiding the risk of loose fibers, rigid board materials must typically be kerfed to enable the material to be shaped and sized for the particular duct.